Question [HELP]can't stop copying file to Phone

Hello. I'm sorry if i posted in the wrong section (Move to the right section for me)
I can't copy/cut file to PHONE MEMORY/SD CARD

HOW THIS HAPPEN

I TRY TO ROOT MY ANDROID AND AFTER ROOTING I CAN'T OPEN SOME APPS
  • PlayStore
  • Gallery
I ALSO CAN'T SWITCH ON
  • WiFi
  • Portable Wi-Fi hotspot
When i try to switch on wifi/hotspot, it will automatically switch it off
I think to solves this problem is by using custom ROM.
Suggest me the best custom ROM.
BTW, i hope i can fix this problem without using custom ROM.
VERY NEED HELP FROM YOU GUYS

Too bad i can't post link for screenshot and video

My Device:
Samsung Galaxy Mega (GT-i9205)

Hope can solve this faster

Thanks,